1. Carex laevivaginata (Kükenthal) Mackenzie in N. L. Britton and A. Brown, Ill. Fl. N. U.S. ed. 2. 1: 371. 1913.
Carex stipata Muhlenberg ex Willdenow var. laevivaginata Kükenthal in H. G. A. Engler, Pflanzenr. 20[IV,38]: 172. 1909
Plants with basal sheaths of previous year not persistent. Culms to 80 cm × 2 mm, scabrous throughout. Leaves: sheaths all with blades, fronts smooth, lacking spots, veinless, apex yellow, thickened, truncate, cartilaginous, entire; ligules acute, 5 mm, free limb to 0.5 mm; blades yellow-green, epistomic, to 60 cm × 6 mm, papillose adaxially (25X). Inflorescences densely spicate, cylindric, elongate, with 6–15 distinguishable branches, 3–6 × 1.5 cm; proximal internode to 10 mm; proximal bracts setaceous, apparent. Scales hyaline. Perigynia pale brown, red-brown distally, with red-brown veins, 10–12-veined abaxially, 7-veined adaxially, to 6 × 2.6 mm, base slightly distended proximally, cordate; stipe to 0.2 mm; beak to 2.5 mm, margins serrulate. Achenes ovate, 2 × 1.3 mm; stalk to 0.3 mm; persistent style base cylindric, 0.3 mm. 2n = 46.
Fruiting May–Jun. Seasonally saturated or inundated soils in wet meadows, marshes, edges of tidal marshes, swamps, or alluvial bottomlands, particularly on calcareous substrates; 0–1500 m; Ont.; Ala., Ark., Conn., Del., D.C., Fla., Ga., Ill., Ind., Iowa, Md., Mass., Mich., Minn., Mo., N.J., N.Y., N.C., Ohio, Pa., R.I., S.C., Va., W.Va., Wis.
Carex laevivaginata is readily distinguished from all other species in the section by the thickened, yellow sheath apex and the papillose, epistomic leaves.